The primary tool used all over the world for precise time transfer (comparisons of atomic clocks and atomic time scales) are special timing GNSS receivers. Such receivers require precise calibration with sub-nanosecond accuracy. It is necessary to eliminate a systematic error related to the delay of the received signal through the antenna and receiver electronics. For different receivers, these delays range from tens to several tens nanoseconds, and precise measurements are required to determine these delays with high accuracy. The goal of the project is to create a center which will calibrate such receivers, primarily using European Galileo, but covering as well other satellite navigation systems - GPS, GLONASS and Beidou.